When testing emails I use Litmus and various testing accounts and mobile responsive designs render fine. For exmaple a desktop html will contain 3 CTA buttons side by side, when presented on mobile devices they stack. If sent to the client through their corporate system, the renderring breaks. So I can send exactly the same email to two mailboxes on my Nokia, the first is a Gmail address and the second is my work address. the Gmail html looks fine but the work html doesn't render correctly. Remember this is viewed on exactly the same device, in exactly the same mail client.

Has anyone experience of this, any fixes?

Nigel.